In addition to the well-known 11Σ+ and 21Σ+ electronic states which are nonadiabatically coupled and responsible for the ionic-covalent transition in lithium fluoride (LiF), the lowest-lying Π state is included in the present dynamical treatment. Although this purely repulsive 11Π state lies energetically close to the 21Σ+ one and has a remarkable transition dipole moment with the 11Σ+ ground electronic state in the Franck-Condon region, it is often excluded in studies on the photodissociation of LiF. Here we demonstrate the important role of 11Π by comparing two-state (11Σ+ and 21Σ+) and three-state (11Σ+, 21Σ+ and 11Π) nuclear dynamical simulations focusing on the electronic state populations. Both for short (τ = 20 fs) and long (τ = 100 fs) laser pulses in the energy interval of ℏω=6.2eV–7.35eV we find that the population of 11Π can significantly exceed that of 21Σ+. Furthermore we consider rotating molecules and reveal a faster dissociation compared to the case where only the vibration of the molecules are treated (recently found in J. Chem. Phys. 144 (2016) 044107).
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry